This invention relates to a method and apparatus for regulating the sealing pressure between refractory plates of a sliding nozzle which controls the flow of molten metal from the pour opening of a molten metal vessel such as a ladle, a turndish or a converter furnace.
The conventional methods for achieving the above purpose have been described in publications such as U.S. Pat. No. 311,902, Japanese Pat. SHO 39-2215, Japanese Pat. SHO 45-20587, and Japanese laid-open application 48-6982 and so on.
However, the above methods share the same defects in mounting the refractory plates.
Namely, for the purpose of obtaining completely tight sealing between the plates, the sliding surface of the sliding refractory plate and the corresponding surface of the stationary refractory plate must be polished to a flatness or surface finish of less than 0.05 mm.
Another important condition for facilitating the complete sealing of the refractory plates besides the flatness or surface finish of the plates is the sealing pressure, namely the pressure which obtains at the interface of the plates.
The following are conventional methods for applying the above sealing pressure:
(1) fastening the upper and lower metal frames by nut and bolt means, PA0 (2) fastening the upper and lower metal frames by a combination of springs and nut and bolt means, PA0 (3) fastening the upper and lower metal frames by toggle mechanisms.
In the first and second methods, the nuts and bolts are fastened by a torque wrench, however, the sealing pressure which is substantially a very important factor in achieving complete sealing, can not be determined accurately due to the friction or wear on the threads of the nuts and the bolts.
In the third method, the toggle mechanism cannot constantly maintain the desired sealing pressure between the refractory plates when the thickness of such refractory plates varies due to wear or due to variations in size which occur during the production thereof.
Furthermore, the above method requires heavy manual labor in a high temperature atmosphere.
It is an object of the present invention to provide a method which resolves the aforementioned disadvantages and wherein complete and stable sealing can be obtained between the refractory plates without necessitating any manual labor.
It is another object of the present invention to provide a method for applying a desired sealing pressure between the refractory plates of a sliding nozzle which is characterized in that a lower metal frame which encases the sliding refractory plate is urgingly pressed toward a fixed metal frame which encases the stationary refractory plate by a desired press means which can be replaceably mounted relative to the sliding nozzle so that the desired sealing pressure can be obtained between the refractory plates without necessitating manual labor.
It is still another object of the present invention to provide a sliding nozzle device which includes a mechanism for replaceably mounting the press means and another mechanism for maintaining the sealing pressure between the refractory plates once the desired sealing pressure has been obtained by the press means.
It is a further object of the present invention to provide a sliding nozzle device for achieving the objectives of the above method wherein the device is characterized by improvements formed on each substantial part or constituting element of the device such as the refractory plate, the sliding mechanism or the spring means.
It is still a further object of the present invention to provide a method for applying a desired sealing pressure between the refractory plates of a sliding nozzle wherein the press means which urges the lower metal frame toward the upper metal frame is provided with a hydraulic pressure gauge so that the desired and accurate sealing pressure can be constantly maintained between the refractory plates.
The above and further objects of the invention will more fully appear from the following detailed description of the invention when the same is read in connection with the accompanying drawings.
It is to be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the invention.